Irritable bowel syndrome (IBS) is not a disease, but a functional disorder. In IBS, the colon is affected by motor dysfunction. The nerve fibers in the colon of individuals with IBS are thought to be hypersensitive. This dysfunction causes the symptoms of IBS, such as constipation and diarrhea. Individuals with IBS may also have abnormalities in the normal flora in the colon, which can further aggrevate the symptoms of IBS.
Improper function and hypersensitivity of the colon may be due to many factors. Stress, food triggers, drugs, emotions, and hormones may all contribute to the onset of this condition. There is no underlying disease or cause for IBS. Because of this, IBS is typically seen as a diagnosis of exclusion. IBS can be diagnosed only after a physician has ruled out other possible causes of the symptoms..
Irritable bowel syndrome affects both men and women, though it affects women more. It is usually diagnosed in between the ages of 20 and 30 years, but may be diagnosed into the 60’s. Over the past decade, IBS has become more prevalent in children and young adults. 
Individuals with irritable bowel syndrome can have a wide variety of symptoms. The most common complaints are; constipation, bloating, gas, abdominal pain, diarrhea, and mucous in the stool.
There are two main clinical types of IBS:
- The first is constipation predominate. In this form of IBS, the patient has constipation that fluctuates with normal stool frequency. They often suffer from an increased pain in the lower abdomen, especially on the left side, and is relieved by a bowel movement. The stool often has excess amounts of mucous. These patients also can complain of bloating, flatulence, nausea, and dyspepsia.
- The other clinical type is diarrhea predominate. These individuals will have diarrhea that is urgent on rising and after meals. Patients will also have pain, bloating, and incontinence. 
- It is estimated that 35 million, or 1 in 5 Americans, has IBS
- Even though 10-20% of Americans are affected by IBS, only 15% of them will seek treatment
- Women are more likely than men to seek treatment. Irritable bowel syndrome accounts for more than 3 million doctor visits each year. 
The goals of conventional irritable bowel syndrome treatment are supportive and palliative. It is very important to have a good physician-patient relationship due to the complex nature of IBS. In most cases, treatment consists of education about the precipitating factors that contribute to the symptoms of IBS. The patient is instructed to avoid these triggers. Dietary advice, fiber, and stress reduction are readily utilized.
In severe cases, medications that decrease the spasm or activity (antispasmodics) in the colon that precipitate pain can be prescribed. For cases of severe diarrhea, anti-diarrheal drugs can also be prescribed. In some cases, antidepressants are also utilized to provide a relief of both pain and bloating.
Alternative treatment is focused on decreasing the symptoms of the condition by treating possible causes. Because so little is known about the etiology of IBS, treatment can be difficult. Also, because there is not a nutrient or structural defect involved in the development of the disease, treatment with specific vitamins and minerals has little to no effect.
Peppermint oil has been widely researched and studied as an effective treatment of IBS. Peppermint oil is anti-spasmodic in nature. It relieves the smooth muscle spasm in the GI tract that can cause constipation and diarrhea. Therefore, it is an effective treatment for IBS when the colon becomes hypersensitive to certain triggers. In order for the peppermint oil to reach the colon and not be digested by the stomach acids it must be enteric coated, which allows it to pass into the intestines undigested. Peppermint oil is helpful for almost every case of IBS.
In one study, 79% of participants who took peppermint oil reported a decrease in the severity of pain, and 56% became pain free with continued administration of the oil. Other results from this study include; 83% of participants reported a decrease in bloating and stool frequency, while 73% had decreased belching, and 77% had decreased flatulence.  Peppermint oil was found to be safe and well tolerated with very few reported side effects.
Peppermint oil has also been studied in children. In one particular clinical trial, 75% of children reported a decrease in the severity of pain associated with IBS during the symptomatic stage.  Another study in children found that it was useful in the reduction and prevention of recurring abdominal pain often associated with IBS. 
In addition, a single case study found that peppermint oil exhibits some antimicrobial activity. The administration of peppermint oil resulted in an improvement in IBS symptoms by reducing the overgrowth of bacteria. 
Fiber is a recommended and standard treatment for any patient with IBS. Fibers increase the transit time for patients with constipation and can also be used to bulk up the stool for patients who are more prone to diarrhea.  The dose of fiber needs to be tailored to the individual to avoid over supplementing, which can lead to constipation with an over extended bowel. Suggested fiber choices are pysllium husk, oat bran, wheat bran, and fruit pectin. 
A suspected cause, or contributing factor to IBS, is the overgrowth of unhealthy bacteria in the intestine. Our intestines have normal healthy flora present in large amounts to help decrease the amount of space that unhealthy bad flora can grow in. When antibiotics impact the normal flora, for example, the unhealthy flora moves in and overpopulates. This overpopulation is believed to contribute to the hypersensitivity of the colon.
One study found that healthy bacteria, Bifidobacterium, was decreased compared to healthy controls in patients with IBS. It also found that there were increased levels of Enterobacterium, an unhealthy bacterium in the intestines of IBS patients, compared to controls.  Another study measured the effects of supplementation of the probiotics Lactobacillus and Bifidobacterium. 38% of the participants had a decrease in pain after 2 weeks and 52% had a decrease after 4 weeks. The severity of pain was decreased by as much as 49% overall.  I n a study using Lactobacillus only, every patient had a resolution of pain and IBS symptoms were improved in 95% of participants. Supplementation also helped to improve constipation and to normalize the frequency of bowel movements. 
Artichoke leaf, Cynara scolymus, has been historically used to relieve dyspepsia. Because individuals with IBS can have dyspepsia, artichoke leaf has been researched as a possible treatment. In study, Artichoke leaf was supplemented at 500 mg/day in the form of powdered extract in patients with IBS. Not only did the artichoke leaf relieve the dyspepsia, it also resulted in an overall decrease in the severity of all the symptoms of IBS. 96% of participants also rated Artichoke leaf as a better treatment than previously tried methods. 
Arrowroot is a plant starch. It is used as a fiber source in its ground, powdered state. In one particular study, individuals with diarrhea predominate IBS were supplemented with arrowroot for one month. After the treatment period, participants reported a decrease in the frequency of diarrhea with a long-term effect on limiting periods of constipation. Participants also reported a decrease in abdominal pain. The mechanism of action is believed to be due to bulking the stool. 
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